FIG. 1A shows a typical decompression or recompression treatment pressure vessel 10 for human occupancy. FIG. 1B shows an end view of the pressure vessel shown in FIG. 1A. As shown in FIG. 1A, the pressure vessel 10 is divided into two sections, an inner treatment chamber 12 and an outer airlock chamber 13. Each of the treatment chamber and airlock chamber is closed by a swing door 30. In FIGS. 1A and 1B, a known supply or medical lock 20 is shown. The supply/medical lock 20 is typically a round cylindrical pipe that penetrates into the pressure vessel 10 with a door each at the inside and outside end. The outside door 24 is outwardly hinged by means of winged bolts, tension clamps, breach lock, etc. and is externally pressed against a flange around the cylindrical pipe. The disadvantage of this known supply/medical 20 is that it is not self-locking and its air-tightness depends on the integrity of the bolts/clamps in compressing the door seals against the door flange. Further, these door locking parts are heavy and bulky, and they require regular inspection and maintenance. As the pressure inside the pressure vessel 10 and also the medical lock 20 is higher than ambient most of the time, there is always a force tending to open the outside door 24 outwardly. For safety purposes, a safety interlock mechanism has to be provided at the outside door 24.
During decompression or recompression treatment, a patient may be accompanied by a doctor. Such treatment in these enclosed chambers may take many hours. During treatment, the patient may require food, drink or medicine, which must be transferred into these enclosed chambers without affecting the treatment chamber's pressure; such supplies are delivered, for example on a tray, through the supply, medical or transfer lock.
It can thus be seen that there exists a need for a new medical or supply lock that is robust in design and which can overcome the disadvantages of the existing prior art.